It was part of a longer trip but from arriving in Greece to returning to the channel was maybe three months for me. I was by no means attempting to stick to a time limit, however, and cycled fairly leisurely (40-50 miles a day) and frequently took days off/detours as the mood took me. I had a whole week's holiday in Halkidiki, north-eastern Greece, for example, as well as four days in Budapest.
General thoughs on the accommodation:
Turkey: I only spent a couple of days there but generally hotels were fairly cheap and plentiful - about £25 when I was there, I think. Worth stopping in Edirne on your way down just for the cultural shift - amazing place.
Bulgaria: Very cheap (outside Sofia) and generally disgusting. Cockroaches in rooms and in restaurants in most of the little towns. I did get a few nice ones though - £12 a night in what would be 5* over here - king-sized bed, lounge area, massive bathroom, all newly refurbished. I stayed two nights! That was in Vratsa, north of Sofia. A great town and the ride up the valley from Sofia was stunning - despite having four p*nctures!
Serbia: See Bulgaria, without the nice ones.
Romania: Surprisingly better than Bulgaria but not as cheap as you might think - around £25-30 per room. Timisoara is the town to hit if you go that way. Quick note on Romania - I was advised by many people not to go there because it's 'dangerous, full of thieves, you'll get lynched' etc., but I'm very glad I did. The countryside is beautiful and it's just such a different world - they tend their fields by hand, most of the traffic in the villages is horse and cart. But it's not got the feeling of poverty that areas of, say, Bulgaria and Serbia have, where you often see people picking through rubbish tips etc. Romania has a more serene, contented feel. Quite a magical place - and I didn't get lynched or robbed.
Hungary: much like Germany/Austria in many ways, including the hotels, although perhaps slightly cheaper - like Romania prices. Plentiful and of varying quality, but never as bad as Bulgaria.
Slovakia: A step down from Hungary in terms of price, apart from Bratislava, naturally. An interesting country - really liked it there.
You'll generally have no problem finding somewhere to stay - there's always a hotel of some sort.
I didn't really camp at all through that stretch, for various reasons. Mostly because I wanted to use my time 'off the bike' as best I could, exploring the towns and cities along the way and just seeing what life was like there. I'd see enough of the 'country life' in the days, from the saddle, and wanted to immerse myself in the other side in my evenings/days off. Obviously not the cheapest way of doing it but I got more out of it that way, I think. All depends on your own motivations.
Decent maps of Hungary/Romania/Bulgaria were fairly hard to come by out there - I'd get them in Germany/Austria if you can. Saying that, though, navigation isn't a huge problem - there's just not that many roads!
I'm reluctant to suggest or recommend anything in particular as it really depends on you. I really enjoyed that section of my ride - it was hard at times and some of the places I stayed weren't the nicest or the most inviting, but that was part of why I wanted to go out there - to experience it, just see what it was like.
